@aurum/cache: getcrf asks for filename when called for a commit buffer,
it also performs bad when file is 0
@aurum/cmdutils: Add new getrrf action: getsilent: it doesn’t ask for a filename
autoload/aurum: Respect the situation when repo is not 0, but file is 0

autoload/Powerline: Added aurum:status segment (requires changes to colorscheme to work)
autoload/aurum: Cached reltorepo call
Made aurum#status() use empty string in place of zero
@aurum/drivers/git: Make rf-status() work in statusline

@aurum/drivers/*, @aurum/log: Now using revrange() only to get revisions range, purged out support for numeric arguments to revrange() (!!this function is not tested anymore for git driver), made returned value of getchangesets() be used